Production of heating oils



1941- G. A. LLOYD, JR., ETAL 2,252,982

PRODUCTION OF HEATING OILS Filed March 7, 1939 2 Sheets-Sheet 1 55 ONDA R Y, BUBBLE Tom/ER P2 /MA 2: 9 30.331. 5 7"0 WER SOAKl/VG COOLER HE A TING Co/L TOTAL FEED u/ve/ 'REnu/v 1, W41; G. A. LLOYD, JR, ETAL 2,252,082

PRODUCTION OF HEATING OILS Filed March 7, 1959 2 Sheets-sheet 2 Patented Aug. 12, 1941 PRODUCTION OF HEATING OILS George A. Lloyd, Jr., Elizabeth, and Eugene C.

Hermann, Westfield, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application March '7, 1939, Serial No. 260,274

5 Claims.

The present invention relates to a process for the production of high quality petroleum products boiling in the heating oil range. In accordance with the process of the present invention, the relatively unstable petroleum constituents boiling in the heating oil range are segregated from the relatively stable constituents and treated in a manner to increase their stability. The treated constituents are then subsequently blended with the by-passed' relatively stable constituents.

It is well known in the art to produce petroleum products boiling in the heating oil range by various processes. For example, in order to produce heating oil products of suitable characteristics, it is known to segregate the fraction from a point in a cracking system. These heating oil fractions are usually produced when processing petroleum distillates, as for example, gas oils, furnace oils, and reduced crudes in cracking operations. It is the usual practice to pass the petroleum feed distillate, as for example, a gas oil, through a furnace under conditions adapted to cause the cracking of the feed oil. The heated distillate is then passed into a soaking drum or reaction chamber in which the oil is held under cracking conditions for a sufiicient length of time to substantially complete the cracking reaction. The cracked distillate is then passed to a so-called tar separator in which tar of the desired gravity may be withdrawn. The overhead products iromthe tar separator are then usually led into a primary bubble tower. A cycle stock is withdrawn from the bottom of said primary bubble tower and recycled to the coil. The overhead from said primary bubble tower having an end point of about 600 F. or 700 F. is then led into a secondary bubble tower. Naphtha distillate and gas is withdrawn from the top of said secondary bubble tower while a so-called heating oil distillate is withdrawn from the bottom of said secondary bubble tower. The heating oil distillate is then acid treated, rerun, sweetened, and filtered in order to produce a suitable heating oil product.

We have now discovered a method by which it is possible to economically produce a heating oil product of higher quality and increased stability. We have discovered that the relatively lower boiling fractions of said heating oil product are relatively unstable as compared to the higher boiling constituents. These lower boiling constituents break down and deteriorate, ,unless treated, causing sedimentation and impairing the quality of the heating oil product. This is extremely undesirable since burners are affected and the burning efficiency of the oil is materially lowered. In order to prevent this, it has been the usual practice to treat the entire heating oil fraction. This, however, has not been entirely satisfactory since the relatively large amount of the heating oil had to beprocessed, thus requiring considerable quantities of treating reagents.

We have now discovered that if the relatively lower boiling constituents are segregated and treated in a manner to increase their stability, it will be unnecessary to treat the relatively higher boiling constituents. Thus, in accordance with ourprocess, it is possible to produce a higher quality product which will not deteriorate in use or storage and to effect considerable economies in the production of heating oil products.

The process of our invention may be readily understood by reference to the attached drawings illustrating one modification of the same. Figure 1 illustrates a diagrammatical flow plan of a normal cracking operation. Figure 2 is specific to the invention and illustrates a modification in which the same may be. carried out.

Referring specifically to Figure 1, for purposes of illustration, it is assumed that the feed stock is a gas oil distillate boiling in the range from about 400 F. to 700 F. and having a gravity of about 32 A. P. I. The fresh feed is introduced into the lower part of primary bubble tower 2 by means of feed line I. The feed together with cycle oil is withdrawn from the bottom of primary bubble tower Z by means of line 3 and is introduced into heating coil 4 in which the temperature is raised to cracking conditions. The heated oil is withdrawn from heating 'coil 4 by means of line 5 and introduced into soaking drum or reaction chamber 6 in which the oil is held under cracking conditions for a sufficient length of time to produce optimum conversion of the feed. The down-fiow soaking drum operation is illustrated, but it is to be understood that either a down-flow or an up-flow operation may be employed. The products are withdrawn from reaction drum 6 by means of line I and passed through a pressure release Valve 8. The products under reduced pressure are released into evaporator or tar settler 9. Tar of the desired gravity usually from about 8 to 12 A. P. I. may be withdrawn from evaporator 9 by means of line 2 I. The vapors pass overhead from evaporator 9 through vapor line I!) into primary bubble tower 2. Cycle stock accumulates in the bottom of primary bubble tower 2 and vapors pass overhead through vapor line ll into secondary bubble tower l2. The temperature at the top of the primary bubble tower 2 is so adjusted to secure the desired end point in the products withdrawn from the bottom of secondary bubble tower I2. The temperature atthe top of tower I2 is controlled so as to produce an overhead distillate of the desired end point which is removed by means of line l3, condensed in cooler 14 and separated from fixed gas in distillate drum l5. Fixed gas is removed from distillate drum l5 by means of line l5 while the overhead condensed distillate from I2 is removed by means of line stream withdrawal accumulator 22 by means of line 23 and are blended with the lower boiling constituents after said constituents are removed by means of line and have been acid treated in 24 and rerun in 25 in a manner to preserve their stability.

Figure 2 illustrates another operation for carryingout the process of the present invention. In accordance with the process as illustrated by Figure 2, conditions are maintained in the cracking coil so that a relatively high gravity tar A. P. I. is secured from the evaporator. Thus, in accordance with this process, the relatively higher boiling constituents are included with the cracking coil tar and are withdrawn from the cracking coil evaporator 9 by means of line 2|. The relatively lower boiling constituents of the heatingoil are withdrawn from the bottom of the secondary tower l2 by means of line 20. The

Heating oil is usually withdrawn from the.

lower boiling constituents are acid treated in treating unit and then introduced into rerunning equipment 32 by means of line 3|. The relatively lower boiling constituents of the heating oil are taken overhead from 32 by means of line 33 and introduced into sweetening unit 34. The tar withdrawn from the cracking coil evaporator 9 by means of line 2|, containing the relatively higher boiling constituents of the fuel oil is introduced into fractionating unit 35. Conditions are maintained on fractionating unit 35 so that a tar of the desired gravity is withdrawn by means of line 36 and the heating oil constituents of the desired end point are removed overhead by means of line 37. With various feed oils under certain conditions, it may be desirable to rerun the heavy heating oil in rerun unit 38, although it is generally preferred to blend said constituents without rerunning with the overhead from the rerun still 32. The blend of the treated relatively low boiling heating oil constituents and by-passed relatively high boiling heating oil constituents is sweetened in sweetening unit 34, withdrawn by means of line 45, and then filtered in filtering unit 39. The finished heating oil product is withdrawn by means of line 4|.

It is to be understood that the processes of the present invention may widely vary. The invention is particularly adapted for the production of heating oil petroleum products having a gravity in the range from about 25 to 40 A. P. I. and boiling in the range from about 350 F. to "750 F. It is readily applicable to the treatment of high sulfur, low sulfur gas oils, furnace oils, and the like. The amount of heating oil bypassed will depend upon the particular crude or feed stock from which the heating oil is derived and the cracking conditions, as well as upon the yield and quality of the heating oil products desired. In general, it is desirable to by-pass from about 25% to of the total heating oil distillate around the acid'treat. For example, it is desirable to produce from 25% to 50% of the heating oil produce from side stream withdrawal accumulator 22 or to include this quantity in the tar withdrawn from tar separator and to produce from 50% to 75% from the bottom of the secondary tower. When producing heating oil boiling in the range from 350 F. to 650 F., we have found that it is desirable to treat for stability the constituents boiling lower than about 500 F. or 550 F. The invention is particularly applicable in the production of heating oils boiling in the range from about 350 F. to 625 F. When producing a heating oil of this character, we

have found that it is desirable to produce approximately 40% to of the oil from the bottom of the secondary tower and to treat this fraction for stability and to separate the remainder of the relatively higher boiling heating oil constituents from either the accumulator in the primary bubble tower or to separate this quantity with the tar as described above. The temperatures and pressures maintained on the cracking system will depend'upon the particular feed stocks being cracked, the yield of other products desired, as well as upon the yield and quality of heating oil desired. The following data illustrate typical operating ranges when withdrawing the entire heating oil fraction from the bottom of thesecondary tower as compared to operating ranges when withdrawing the higher boiling heating fractions with the tar and from the side stream withdrawal accumulator in the primary tower.

Table 1 Higher heating oil fractions Higher heating Normal withdrawn oil fractions operation from side withdrawn stream with tar accumulator Feed stocln. Gas 011 Gas oil Gas oil Boiling range, initial, about F'. 400 400 400 90% distilled, about F. 700 700 7 Gravity 28-93v 28-33 Total feed- 18, 000 18, 18, 000 Fresh ieed. 35-55 a 35-55 35-55 Coil outlet temperature. 890-940 890-940 890-940 Soaker temperature... 850-900 850-900 850-900 Soaker pressure 500-1000 500-1000 500-1000 Evaporator temperature-top 650-750 650-750 600-700 Evaporator temperaturebottom 690-790 690-790 640-740 Pressure 95-115 95-115 95-115 Tar gravity 9-11 9-11 19-21 Temperature at top of primary tower. 520-600 470-550 470-550 Temperature at bottom of primary tower. 570-650 520-600 520-600 Primarytower pressure. 90-110 90-110 90-110 Temperature at top of secondary tower.... 375-425 375-425 375-425 Temperature at bottom of secondary tower 425-475 425-475 425-475 Pressure ..pounds per sq. in.. 95-105 95-105 95-105 Table 2 Higher heating oil fractions Higher-heating Normal operawithdrawn oil fractions tion from side withdrawn stream from tar accumulator Feed stock Reduced cru Reduced crude Reduced crude Boiling range, initial, about F 450 450 450 50% distilled, about ..F.. 700 700 700 Gravity A. P. I. 4-20 14-20 14-20 Total feed. .volume per hour. 25, 000-30 000 25, 000-30, 000 25, 000-30, 000 Fresh feed percent.. 60 60-80 Coil outlet temperature 865-910 865-910 Soaker temperature 835-880 835-880 835-880 Soaker pressure ..pounds per sq. 1 2 200 200-500 Evaporator temperature-top. 0- 750-825 700-775 Evaporator temperaturebottom 760-335 760-835 7 -785 Pressure 9 115 95-115 95-115 Tar gravity 10-12 10-12 19-21 Temperature at top of primary tower- 520-600 0 0-5 0 Temperature at bottom of primary towe 620-700 570-650 570-650 Primary tower pressure -1 0-110 90-110 Temperature at top of secondary towe 375-425 375-425 375-425 Temperature at bottom of secondary tow 425-475 425-475 425-475 P re pounds per sq. in.. 5 5-105 95-105 The particular method of treating the heating atively lighter boiling constituents were removed oil to insure its stability and. to prevent sedimentation and deterioration may likewise be widely varied. The usual method is to treat this fraction with from 2 to 5 pounds of sulfuric acid of from 88 to 98 concentration per barrel of oil. Thus, in accordance with the process of our invention, it is possible to save from 25% to of the acid and to materially increase the overall capacity of the entire operation. The acidtreated heating oil is then rerun in order to separate higher boiling constituents and to secure the desired end point in the product. Usually, from 85% to 95% of the acid-treated heating oil is taken overhead in the rerurming unit. The overhead heating oil of the desired end point is then sweetened with caustic soda and then clay filtered in order to remove any sediment and the like.

In order to further illustrate the invention, the following example is given which should not be construed to limit the same in any manner whatsoever. In one operation, heating oil was produced by the normal operation; that is by segregating the entire fraction from the bottom of the secondary bubble tower, acid treating the same, rerunning, sweetening, and then filtering. In another operation, approximately 50% of the relatively higher boiling constituents was withdrawn from the evaporator with the tar, resulting in a tar gravity of about 20 A. P. I. The relfrom the bottom of the secondary tower in the usual manner. The tar was fractionated to sepstrate the higher boiling constituents which were subsequently blended with the acid-treated, lighter boiling fraction. The inspections of the heating oil secured by the respective processes are as follows:

Method Split dis- Current Hate Gravity A. P. I-. 32. 3 32.0 Tmtml 348 354 10% distilled at F-. 415 416 20% d st lled at- F.. 438 440 F-- 454 459 F.- 471 472 F.- 485 488 F.- 499 502 F- 516 520 F.. 534 539 F.. 569 577 616 618 -percent-- 98 98 do 21 20 "Current method-Heating oil distillate taken from secondar tower bottom acid treated with 2# 98 acid, 1' y swiiesteikiddivkinmmrefi erun Overhead I p 1 1s ate.-- eating oil distillate rerun 0-10 disc 03019}, dtreattledt 1210! 98% gnddrefrun to; 5?, bottiom. The te ezogii fi e W1 e over ea rom e reate the blend sweetened. and mum product and The process of the present invention is not to be limited by any theory or mode of operation but only by the following claims in which it is desired to claim all novelty insofar as the prior art permits.

We claim: I

1. Process for the production of heating oils of increased stability, comprising separating from a cracked distillate boiling in the range from about 350 F. to about 650 F., about 40-60% of the relatively lower boiling constituents from the relatively higher boiling constituents'subjecting said lower boiling constituents to an acid treatment of about 2 to 5 lbs. of sulfuric acid, of from about 88 to 98% strength, per barrel of oil, without subjecting said higher boiling constituents to acid treatment, and blending the treated lower boiling constituents with the untreated higher boiling constituents.

2. Process in accordance with claim 1 in which said relatively low boiling constituents are segregated from higher boiling constituents by withdrawing said higher boiling constituents with the tar from a cracking operation.

3. Process in accordance with claim 1 in which ation.

4. A method for treating heating oils to produce heating oils having increased stability which comprises separating a heating oil fraction boiling in the range from about 350 F. to about 650 F., into two fractions comprising a lower boiling fraction and a higher boiling fraction, subjecting the lower boiling fraction to acid treatment to remove undesirable and unstable constituents therefrom, and blending the treated lower boiling fraction with the untreated higher boiling fraction to produce a heating oil having increased stability.

5. A method in accordance with claim 4; wherein the lower boiling fraction has a boiling range of about 350 F. to 500 F. and the higher boiling fraction has a boiling range of about 500 F. to I650'F.

GEORGE A. LLOYD, J R. EUGENE C. HERMANN. 

